McLaren 720S Service Manual — Built by an Owner Who Wrenches on One

I built this site because I own a 720S and got tired of paying dealer rates for work I could do myself — if only I had the documentation. The McLaren Service Information System (SIS) is factory software that dealers pay a subscription to access. Independent shops and owners are locked out entirely. That struck me as wrong, so I reconstructed the entire thing and put it online, free.

What you'll find here is the complete, navigable SIS for the 720S: every repair procedure, every wiring diagram, every torque spec, every TSB. The same documentation a McLaren technician opens on their workshop laptop — just running in your browser instead.

What's in the Manual

The SIS covers the 720S from its 2017 introduction through current production. It's organized the same way McLaren organized it: by vehicle system, then by document type within each system. Here's what you can actually access:

• Repair Instructions (RI): Step-by-step remove/install procedures for every serviceable component. These aren't summaries — they're the full procedure with numbered steps, warning callouts, and cross-references to prerequisite work.
• Torque Settings: Every fastener spec in the car, organized by system. Before I found this, I was running procedures from forum threads where someone would write "I think it's about 85 Nm" for a suspension wishbone bolt. That's not good enough on a car like this.
• Wiring Diagrams: Full circuit diagrams for every electrical system — with pin assignments, connector locations, and signal flow. Searchable by component or circuit name.
• Diagnostic Data: ECU architecture, sensor locations, CAN bus layout, DTC reference. Helpful context even if you're running MDS diagnostics.
• Fluids, Lubricants & Adhesives: Correct spec for every fluid in the car. This matters more than most people realize — wrong hydraulic fluid in the RCC II system, for example, will destroy seals.
• Repair Times (FRM): McLaren's flat-rate times for every job. Useful for getting quotes from independents — you'll know immediately if someone's padding the estimate.
• Special Tools & Equipment: Procedures that require dedicated tooling call it out explicitly. Saves you from getting halfway through a job and realizing you need something you don't have.

Technical Service Bulletins

The TSB list is where I'd point any new 720S owner first. A few of the Knowledge Articles are genuinely important to know before you start turning wrenches — particularly the ones related to the hydraulic system and the airbrake panel bolt torque check (SCB_14_A_003). Don't skip that one.

Common Service Procedures — What I've Learned

These are the jobs I hear about most, either from doing them myself or from the mcltech.net community. The manual covers all of them in full — this is just context to help you find the right procedure.

Engine Oil — M840T Dry-Sump System

The M840T uses a dry-sump lubrication system, which means the oil level reads from the instrument cluster, not a dipstick. Capacity with filter is approximately 8.5 liters. McLaren specifies Mobil 1 5W-40 meeting ACEA A3/B4, and the interval is 12 months or 10,000 miles — whichever comes first. The filter is a cartridge on the passenger side of the engine. One thing that catches people: the oil tank is in the rear of the passenger cell, separate from the block. Make sure you're checking the right thing.

Hydraulic Suspension — RCC II System

This is the one where cutting corners genuinely costs you. The RaceActive Chassis Control II runs on Pentosin CHF 11S — not a generic power steering fluid, not whatever's on the shelf. The system operates at high pressure; there's a full depressurization procedure in the SIS that you must follow before disconnecting anything. Accumulator failure is common on higher-mileage cars — the symptom is reduced ride compliance and increased body roll. The flush interval is 4 years. I did mine at 3 years and the fluid was already noticeably discolored.

SSG Gearbox Fluid

The 7-speed dual-clutch uses Castrol Transmax ATF, shared with the integrated rear differential. Interval is 3 years or 30,000 miles. Overfilling causes erratic shift behavior — be exact with the quantity. The SIS procedure specifies checking level at operating temperature via the fill hole, not cold.

Electronic Parking Brake — Service Mode

Before you disconnect the 12V battery or pull a rear caliper, you must put the EPB into service mode via MDS. If you skip this step, you cannot retract the caliper piston manually and you will damage the actuator motor. This comes up constantly on the forum from people who didn't know. Now you know.

12V Lithium Battery

The 720S uses a lithium-ion 12V auxiliary battery, not lead-acid. It's in the luggage bay. Do not charge it with a standard lead-acid charger — you'll damage it. CTEK and other lithium-compatible chargers work fine. If the car is stored more than 3–4 weeks, put it on a maintainer. A dead lithium in this car causes all kinds of strange fault codes across multiple ECUs.

Understanding the Electrical Architecture

The 720S uses high-speed CAN bus networking across multiple domain controllers. The main ECUs you'll interact with during service are the Powertrain Control Module (PCM), Vehicle Control Unit (VCU), Active Brake Control (ABC) module, and Body Control Module (BCM). For anything beyond reading codes — calibrations, injector coding, adaptations — you need MDS (McLaren Diagnostic System) rather than a generic OBD-II tool. MDS is available to the community through mcltech.net.

The PDU (Power Distribution Unit) is behind the passenger seat. Most circuits are protected by smart fuses within the BCM rather than traditional blade fuses, which means you can't just pull fuses to isolate circuits the way you might on a conventional car. Use the wiring diagrams.

Body Structure Notes

The Monocage II carbon fiber tub is not repairable — any structural damage requires a McLaren assessment. But the outer skin panels (doors, roof, clamshells, decklid) are fully removable and replaceable without structural work. Clamshell alignment is a multi-point eccentric bolt adjustment; the SIS has the full procedure with factory gap tolerances (2mm maximum variation). Door gap adjustment is similarly documented with specific eccentric bolt locations.

Frequently Referenced Torque Values

These come up constantly. Always cross-reference against the specific procedure in the SIS for your build date and spec, but these are the numbers I have memorized from doing this work:

• Wheel center-lock nut: 450 Nm (McLaren single-nut socket required)
• Engine sump drain plug: 40 Nm
• Front upper wishbone pivot bolts: 85 Nm
• Front brake caliper mounting bolts: 195 Nm
• Gearbox drain and fill plugs: 35 Nm
• Driveshaft-to-hub flange bolts: 90 Nm + 90° angle turn
• Cylinder head bolts: multi-stage sequence — see procedure DA-RM-01B001 in the SIS

How to Navigate the Manual

The SIS is organized hierarchically by vehicle system. Use the left-hand tree menu in the app to drill into the system you're working on. Each procedure is assigned a document ID in the format DA-RM-[system]-[subsystem]-[number]. The search function (shortcut: Ctrl+K) covers all 5,885 procedures with real-time fuzzy matching — search by component name, part number, or procedure type. On mobile it works fine for reference, but the wiring diagrams really need a larger screen.